Portion of a shoe midsole



FIG. 1 is a perspective view of a portion of a shoe midsole showing my new design;

FIG. 2 is a side view thereof;

FIG. 3 is a top view of a shoe showing a portion of my new design; and,

FIG. 4 is a rear view of a portion of a shoe midsole showing my new design.

The broken lines showing of the remainder of the shoe are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a portion of a shoe midsole, as shown and described. 